1. Field of the Invention
The present invention relates to a multi-output oscillator and a method of generating multiple outputs, and more particularly, to a multi-output oscillator outputting multiple frequencies using a single frequency that is output from a single oscillator, and a method of generating multiple outputs using the same.
2. Description of the Related Art
In order to transmit super high-speed data of 10 Gbps or greater, a broad bandwidth of several GHz or greater is necessary. Such a broad bandwidth may be processed as one channel using a high-speed analog-digital converter (ADC)/digital-analog converter (DAC), or divided into multiple channels and then processed using low-speed ADC/DACs. The high-speed ADC/DAC requires expensive components, and speed-conversion to a low speed for digital processing, and parallel processing, thereby requiring a very complicated configuration. Accordingly, it is easy to implement a radio frequency (RF) system but difficult to implement a digital system. In addition, it is difficult to use various compensation methods, and thus it becomes difficult to realize the performance of the whole system.
On the other hand, it is easy to realize a method using multiple channels into a system, since the performance of the system can be maximized due to the low digital processing speed. However, when the characteristics of various paths in an RF system are to be maintained uniform, it is difficult to realize the RF system and the size of the RF system increases. In regard to the RF system, inclusion of a multi-output local oscillator with various frequencies is critical due to the complexity of the configuration of the RF system and difficulty in realizing the RF system. In particular, for the multi-output local oscillator, a simple structure, a compact size, and minimized variation in the performance of each channel are essential.
A multi-output oscillator employed in a conventional RF transceiver is implemented by arranging an individual oscillator for each frequency or by a structural solution of reducing the number of oscillators by including frequency multipliers and frequency dividers. When using the individual oscillators, an appropriate oscillator for each of the frequencies can be selected and a phase locked loop (PLL) may be used to maximize the characteristics of the multi-output local oscillator, if the range of the output frequency of the multi-output local oscillator is broad. However, the number of PLLs, which is most burdensome in designing a local oscillator, needs to be as many as the output frequencies, and the type of the local oscillator varies accordingly. Thus, the overall size of the RF system increases, and the number of portions that are to be controlled in the RF system increases as much as the number of PLLs.
When a frequency multiplier is used, a great difference is created in the phase noise characteristics of an output signal according to a multiplication number, and generating and mixing signals in a basic oscillator as many as the frequency separations between the output frequencies of a local oscillator is difficult if four or more channels are included, and image components of a mixer need to be removed.